1. Yes you can setup multiple currencies in the cart. First, create 2 pages in your portal and add add the buynow module to each page. Next, configure the first buynow module for US dollars and configure the second buynow module for Euros.
2. Currently, in the cart there is no way for a user to upgrade an existing subscription, they would have to cancel their existing subscription and then purchase the new upgraded subscription. If you would like a quote to add the "upgrade" subscription feature please submit a quote request here http://www.smith-consulting.com/servi... or send an email to sales@smith-consulting.com.
Thanks,